10 - Opth - Squints - Orthoptics + Types of Squint Flashcards
Define binocular vision
using two eyes as a pair to perceive one image
3 grades of binocular vision
Simultaneous perception - by each eye
Fusion - two images fuse to make one, which is maintained with movement
Stereopsis - fused images are seen in depth
define squint
strabismus
deficit of controlled eye movement
2 classifications of squints
manifest OR latent
concomitant OR incomitant
Manifest squint
- features
- suffix
- detection
obvious deviation of eye, visual axis not normally aligned
- tropia
- may be obvious or detected using cover/uncover test
Latent squint
- features
- suffix
- detection
tendency of eyes to deviate- normally aligned
-phoria
detect using alternate cover test
which way is the abnormal eye pointing for these manifest squints
- esotropia
- exotropia
- hypertropia
eso - inward
exo - outward
hyper - upwards
concomitant squint- what and who
remains the same in size and direction in all positions
more common in childhood
Incomitant squint - what + why + when most obvious
changes in different positions of gaze
under action of at least one of the extraocular muscles
most obvious when gaze directed toward affected muscles
2 consequences of squints
diplopia - common if squint develops after visual development (>7y)
suppression - esp if <7y - may lead to amblyopia
Amblyopia - causes?
stimulus deprivation
strabismic (squint)
anisometropic (higher refractive error in one eye)
Amblyopia - mgmt?
can be treated <7y
Tx - occlusion of good eye with patch ~ 6 hours a day
Tx - correction of squint
